A water treatment device which causes electric discharge in water stored in a treatment vessel to purify the water has been known.
For example, Patent Document 1 discloses a water treatment device including a water treatment unit which causes electric discharge in water in a treatment vessel to produce a sterilizing factor in the water, and insulators respectively provided adjacent to an inlet and outlet of the water treatment unit to electrically insulate the water treatment unit and water flowing through the water treatment unit from each other. According to Patent Document 1, the insulators are respectively provided adjacent to the inlet and outlet of the water treatment unit. Thus, no current flows from the water treatment unit to water flowing through the water treatment unit. As a result, supplied power is used efficiently.